Highly viscous liquids have posed a dispensing problem in the art. Vegetable oil containing products have been particularly troublesome. Considerable efforts have been made to provide spray dispensable viscous vegetable oil compositions. These compositions may contain other viscous vegetable based products such as lecithin. These products have been dispensed in aerosol form, generally using a propellant which will mix with the viscous vegetable oil and reduce the viscosity. This has resulted in the use of chlorofluorohydrocarbons (CFCs) propellant. Alternatively, volatile organic compounds (VOCs) such as isobutane or propane have been used. Such propellants are now considered environmentally unacceptable. Pump sprayable dispensing systems for viscous vegetable oil have also generally required dilution of the vegetable oil to reduce its viscosity.
Pump sprayable dispensing systems for viscous liquids have consequently been developed. For example, U.S. Pat. No. 5,088,649 describes a colliding stream hand pump sprayer which can dispense a fine spray of viscous liquids without the need for using diluents. U.S. Pat. No. 5,358,179 discloses a colliding stream sprayer having a molded nozzle. However, the manufacture of such devices can be cumbersome. In manufacture, the two outlets which provide the colliding streams have to be either drilled after molding of the nozzle or formed during injection molding by using releasable pins. Use of molding pins to provide outlet passageways in a nozzle having colliding outlet streams can be problematic. Since the path of the streams intersect, the pins can interfere with one another and be difficult if not impossible to remove. Thus it is desirable to provide a moldable nozzle having two or more colliding streams without using molding pins.
Aerosol containers also have been described in the prior art having colliding streams which improve the break up of viscous fluid. For example, U.S. Pat. No. 5,249,747 describes such a system which uses compressed gases as propellants instead of a CFC or VOC propellant. However, the quantity of liquid product dispensed and the quality of the spray pattern are important. In the prior art, there can be uneven distribution of the viscous liquid and undesirable heavy concentration areas from the colliding stream sprayers.
Accordingly, it would be desirable to provide a hand held dispensing system for viscous liquids which would provide an improved spray pattern which would eliminate any undesirable concentration of product and provide for more even distribution.